By Jonathan Robert Bart, Victoria Helen Johnston
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Additional info for Arctic Shorebirds in North America : a Decade of Monitoring
The x−i were calculated as the simple means of the means/plot because sometimes plots at a camp were not all surveyed the same number of times by rapid surveyors. Camps were widely distributed across the study area, so they were treated as a simple random sample (rather than a stratified random sample). ^ was Under this assumption, the variance of R estimated as ͧ ^− ^ x−, y−) 2Cov( V^(y− ) _________ 2 V(x ) Ϫ V^(R^) ϭ R^ ____ ϩ _____ − xy x−2 y−2 ͨ (12) where 1 2− ^ − 1 2− 1 − − ___ ___ ^ − − V^(x− ) ϭ ___ m s (xi), V( y ) ϭ m s (yi), Cov(x , y ) ϭ m cov(xi, yi) and s2 and coˆv indicate the sample variances and covariances, respectively.
96). Least Sandpipers are considered to be uncommon breeders in the eastern Aleutians (Gibson and Byrd 2007). The species was not recorded in the YDSA or SSA. Although they are spottily distributed in the interior of the Yukon–Kuskokwim Delta, they do not breed in the coastal fringe where we sampled (B. J. McCaffery, pers. ). Pectoral Sandpiper Pectoral Sandpipers were recorded only on the YDSA, where they are a common spring migrant in late May, but only a rare breeder (McCaffery, pers. ). Ten pairs and 19 single birds were recorded, mainly in wetlands.
2). 3). A few dozen pairs and a handful of nests were recorded, but most observations were of single birds and nearly all records were from wetlands. The estimated number of pairs breeding in surveyed plots was 191. In the central part of the Yukon–Kuskokwim Delta, Semipalmated Sandpipers only occur regularly in the lower coastal meadows (R. E. , and C. R. Ely, pers. , B. J. McCaffery pers. ). A few isolated pairs were reported from the sand dunes in the vicinity of Dall Point north of Hooper Bay (Brandt 1943).